Reconstruction of the Cambrian predator and stem-lineage euarthropod Anomalocaris canadensis, based on fossils from the Burgess Shale, Canada. This group shows the precursor of biramous limbs; appendages separated into a ventral and dorsal flap. Reconstruction by Natalia Patkiewicz.

The major findings of the paper are:

Euarthropods (which includes insects, arachnids, crustaceans, trilobites, etc.) are the most abundant and diverse animal group ever, and have significantly affected all of Earth’s ecosystems since their origins.

The fossil record supports a euarthropod origin 550-537 million years ago, close to the most recent molecular estimates.

Combining all strands of fossil record evidence gives an excellent picture of early animal origins and evolution, which is difficult to attain from only one source of fossil data.

This refutes both an ‘instantaneous’ Cambrian Explosion and a ‘long-fuse’ where they originated 650-600 million years ago and diversified later.

If you want to know more, I wrote a short piece for the Oxford Museum of Natural History (here) about its importance, and the press release has also been featured by a number of news outlets, listed below:

Lead-author Allison Daley has also been on the Swiss radio discussing the paper and resultant implications (in French!).

Aysheaia pedunculata, ​from the Burgess Shale, Canada, with undifferentiated soft-bodied limbs. As a close relative of euarthropods, their earliest limbs were similar before their later evolution into the characteristic segmented appendage. Photo credit:​ Allison Daley.